A conventional probing apparatus of such a type, as shown in FIG. 13A for example, includes a loader chamber 1 and a prober chamber 2 adjacent thereto, wherein wafers are transferred from the loader chamber 1 to the prober chamber 2 for performing an electrical characteristic inspection thereon and then returned the inspected wafers to the loader chamber 1. The loader chamber 1 has, e.g., a loading port 3, a wafer transfer mechanism 4 and a pre-alignment mechanism (sub-chuck) 5. Further, the prober chamber 2 has a wafer chuck 6, an alignment mechanism (not shown) and a probe card (not shown). Moreover, a cassette for accommodating therein a plurality of wafers is mounted on the loading port 3 of the loader chamber 1. In the loader chamber 1, the wafer transfer mechanism 4 is driven to transfer wafers sheet by sheet from the cassette. While being transferred, the wafers are pre-aligned by the sub-chuck 5. Then, the pre-aligned wafers are transferred by the wafer transfer mechanism 4 to the wafer chuck 6 of the prober chamber 2. In the prober chamber 2, the wafer chuck 6 moves horizontally and vertically, and the wafers on the wafer chuck 6 are subjected to an electrical characteristic inspection by the probe card. Next, the inspected wafers are returned to their original positions in the cassette via a reverse path. In a probing apparatus for inspecting wafers sheet by sheet, the wafers are loaded sheet by sheet into the loader chamber for an electrical characteristic inspection.
As for a probing apparatus, there has been widely used a probing apparatus having a single loading port as illustrated in FIG. 13A, wherein the loader chamber 1 is disposed at the right or left side of the prober chamber 2 (at the right side in FIG. 13A) and a single loading port 3 is provided at the front side in the loader chamber 1, i.e., at a front surface side of the probing apparatus.
As for another probing apparatus, there has been known a probing apparatus having dual loading ports, which is disclosed in Japanese Patent Laid-open Publication No. S63-081830 (Reference Document 1). In this probing apparatus, a loader chamber respectively having at the right and the left side thereof two loading ports is provided at the front side of the probing apparatus.
The conventional probing apparatus having a single loading port is unable to cope with a recent trend for a high inspection speed for example. Therefore, there is an increasing demand for the probing apparatus having dual loading ports capable of processing wafers in two cassettes consecutively. Accordingly, there arises a need to replace the conventional probing apparatus having a single loading port with the probing apparatus having dual loading ports of Patent Document 1.
However, unlike the loader chamber disposed at the right or left side of the probing apparatus in the conventional probing apparatus having a single loading port, the loader chamber is provided at the front side of the prober chamber to ensure a space for an inker of a marking mechanism in the probing apparatus having dual loading ports of Reference Document 1. In such a configuration, due to an operator manipulating the apparatus at the front side thereof, a wafer transfer line cannot be disposed at the front side of the apparatus and thus the transfer line should be provided at the right or left side of the apparatus, respectively, so that there are various restrictions in modifying the conventional probing apparatus having a single loading port to one having dual loading ports. Accordingly, it is difficult to realize an automatic transfer of wafer between the transfer line and the loader chamber. For example, when the loading port 3 of the probing apparatus shown in FIG. 13A needs to be extended, an additional loading port 3A is provided at a side thereof as shown in FIG. 13B since the sub-chuck 5 is still needed. As a result, a foot print thereof increases.
However, a foot print of an existing probing apparatus may not be further increased due to a limited space in relation with another probing apparatus or the like. Moreover, since the transfer line for automatically transferring wafers has been built to be adapted to the probing apparatus having a single loading port, the foot print is not allowed to be increased when modifying the probing apparatus having a single loading port to one having dual loading ports and, hence, a demand to save the space of the loader chamber is increased.